Second generation mRNA vaccines: Formulation development of mRNA-lipid nanoparticles with TLR9 agonist CpG oligonucleotide adjuvant

WVC 2023 -- Messenger RNA (mRNA) vaccines have attracted increasing attention as a promising and adaptable alternative to conventional vaccine modalities. mRNA vaccine efficacy relies on the vaccine's ability to the reach the cytoplasm of the target cells in high quantities where it can be translated into the antigen of interest. Despite the success of the COVID-19 mRNA vaccines, there is a need to enhance and develop the potential to modulate the immune response of this vaccine modality. In this study, a second generation lipid nanoparticle (LNP) mRNA vaccine was developed by incorporating CpG oligonucleotide (a Toll-like receptor 9 agonist) into LNP formulations. The formulation was optimized using a design of experiment approach and the critical quality attributes (CQAs) of the LNPs were assessed using dynamic light scattering (DLS), electrophoretic light scattering and cryogenic electron microscopy (CryoEM), as well as RNA/DNA encapsulation efficiency assays.